Hydroformylation of 3-methyl-3-buten-1-ol and analogs thereof and use of such hydroformylation products

ABSTRACT

There is disclosed a method of hydroformylating 3-methyl-3-buten-1-ol and analogs thereof with carbon monoxide and hydrogen in the presence of a rhodium compound free from modification by a ligand containing an element belonging to the group V of the periodic table as well as a method of producing 3-methylpentane-1,5-diol and β-methyl-δ-valerolactone using such hydroformylation product.

This is a division of application Serial No. 710,852, filed Mar. 12,1985, now U.S. Pat. No. 4,663,468.

BACKGROUND OF THE INVENTION

1. Field of the Invention:

This invention relates to a method of hydroformylating3-methyl-3-buten-1-ol and analogs thereof and to a method of producingfurther derivatives using such hydroformylation product.

2. Description of the Prior Art:

It is known that, in producing a hydroformylation product by reacting anolefin with carbon monoxide and hydrogen in the presence of a rhodiumcompound, a rhodium compound modified by a ligand containing an elementbelonging to the group V of the periodic table (for example, an organictertiary phosphine such as triphenylphosphine) is used as said rhodiumcompound. In this method, the presence of such ligand contributes toimprovement in stability of the rhodium-carbonyl complex in the reactionsystem. Therefore, this method is advantageous, among others, in thatthe catalyst activity can be maintained for a prolonged period of timeand that the reaction can be carried out under milder conditions, namelyat relatively low temperature and low pressure; hence, said method ishighly useful for commercial purposes (refer to J. Falbe, "CarbonMonoxide in Organic Synthesis", Springer-Verlag, New York, 1970, pages22-25, for instance).

It is also known that 3-methyl-3-buten-1-ol can be used as the olefin tobe hydroformylated with carbon monoxide and hydrogen in the presence ofa rhodium compound (e.g. U.S. Pat. Nos. 3,966,827 and 4,263,449).According to the patent specifications, a rhodium compound modified bythe above-mentioned organic tertiary phosphine is either essential orrecommended as the rhodium compound to be used in the hydroformylationof 3-methyl-3-buten-1-ol. In particular, U.S. Pat. No. 3,966,827describes that the hydroformylation of 3-methyl-3-buten-1-ol in thepresence of a rhodium-carbonyl complex modified by an organic tertiaryphosphine gave 2-hydroxy-4-methyl-tetrahydropyran in about 75-91%yields. These patent specifications do not contain any specificdescription on the hydroformylation of 3-methyl-3-buten-1-ol in thepresence of a rhodium compound free from modification by a ligandcontaining an element belonging to the group V of the periodic table,typically an organic tertiary phosphine.

The hydroformylation of 3-methyl-3-buten-1-ol in the presence of arhodium compound modified by a ligand containing an element belonging tothe group V of the periodic table is very slow in rate of reaction ascompared with the hydroformylation of α-olefins such as propylene and1-octene in the presence of such rhodium compound. Slow reaction ratesmake it necessary to use expensive rhodium compounds in larger amountsand further use larger reaction apparatus and therefore the abovemethods are inadequate as the methods for commercial practice. U.S. Pat.No. 3,966,827 describes to the effect that the residue containing therhodium carbonyl complex modified by an organic tertiary phosphine,which is obtained after separation of the hydroformylation product,2-hydroxy-4-methyltetrahydropyran, from the reaction mixture bydistillation, can be reused for the subsequent hydroformylation.However, rhodium-carbonyl complexes are relatively unstable against heateven in the presence of organic tertiary phosphines capable ofstabilizing the same. Thus, in the step of separating high-boiling2-hydroxy-4-methyl-tetrahydropyran from the reaction mixture bydistillation, the rhodium-carbonyl complexes in such reaction mixture ispartly deteriorated (see U.S. Pat. No. 4,238,419) and, further, thecatalytic activity of said rhodium-carbonyl complexes lowers due toaccumulation of high-boiling byproducts in the distillation residue. Itis therefore very difficult, in the practice of said method, to recycleand reuse the rhodium-carbonyl complexes and the catalysts for a longperiod and in a stable manner. Furthermore, the separation or recoveryof said rhodium-carbonyl complexes having lowered activity from thereaction system, which is required in the practice of the above method,is troublesome and hardly efficient when said rhodium-carbonyl complexeshave been modified by organic tertiary phosphines.

3-Methylpentane-1,5-diol and β-methyl-δ-valerolactone are compounds veryuseful as raw materials in producing polyurethanes and polyesters, forinstance and there is known a method of deriving these compounds fromproducts obtained by the above-mentioned hydroformylation of3-methyl-3-buten-1-ol.

Thus, the above-cited U.S. Pat. No. 3,966,827 and U.S. Pat. No.4,263,449 propose that 3-methyl-pentane-1,5-diol be produced byhydrogenating the hydroformylation product from 3-methyl-3-buten-1-ol inthe presence of a hydrogenation catalyst. On the other hand,β-methyl-δ-valerolactone can be produced by oxidatively dehyrogenating3-methylpentane-1,5-diol at a temperature of 200° C. in the presence ofcopper chromite [Refer to Organic Syntheses, Coll. Vol. IV, 677 (1963)].Therefore, by combining these production methods with theabove-mentioned hydroformylation of 3-methyl-3-buten-1-ol, it ispossible to produce 3-methylpentane-1,5-diol andβ-methyl-δ-valerolactone by using 3-methyl-3-buten-1-ol, which isreadily available in commercial quantities, as the starting material.However, this series of production processes still has a problem fromthe practical viewpoint, for example, in that the reaction rate in thepreceding hydroformylation of 3-methyl-3-buten-1-ol is very slow.Furthermore, the production of β-methyl-δ-valerolactone from3-methyl-3-buten-1-ol requires a complicated production process sinceindependent three reaction steps, namely hydroformylation of thestarting 3-methyl-3-buten-1-ol, the subsequent hydrogenation, andoxidation, are necessary.

In Bull. Chem. Soc. Japan, 35, 986 (1962), it is described thatδ-valerolactone was obtained by subjecting 2-hydroxytetrahydropyran(namely δ-oxyvaleraldehyde) to continuous vapor phase reaction at220°-230° C. in the presence of copper-zinc oxide, copper chromite orcopper chromite-zinc oxide. The present inventors found that the use of2-hydroxy-4-methyltetrahydropyran in lieu of 2-hydroxytetrahydropyran inthis known reaction gives, under the same reaction conditions,β-methyl-δ-valerolactone. Therefore, by combining this reaction with thehydroformylation of 3-methyl-3-buten-1-ol, it is possible to produceβ-methyl-δ-valerolactone by a two-step reaction process starting with3-methyl-3-buten-1-ol. However, when both 3-methylpentane-1,5-diol andβ-methyl-δ-valerolactone are desired to be produced from3-methyl-3-buten-1-ol by using the process just mentioned above, it isnecessary to subject the hydroformylation product from3-methyl-3-buten-1-ol, dividedly in a desired ratio and independently,to the hydrogenation and oxidation steps, respectively. Therefore, forthis purpose, three independent reaction steps, namely hydroformylation,hydrogenation and oxidation steps, are required even when the aboveproduction process is employed. Thus, there still remains unsolved adifficulty that the production process is necessarily complicated.

It is also possible to produce β-methyl-δ-valerolactone by anothermethod, namely by reacting ethyl β,β-dimethylacrylate with carbonmonoxide and hydrogen in the presence of a cobalt catalyst [ChemischeBerichte, 97, 863 (1964)]. However, this method is inadequate for usefor commercial purposes since the separation of the desiredβ-methyl-δ-valerolactone from the reaction mixture containingby-products, such as β,β-dimethyl-γ-butyrolactone, having boiling pointsclose to that of said desired product is not easy and moreover thestarting ethyl β,β-dimethylacrylate is relatively expensive.

SUMMARY OF THE INVENTION

An object of the invention is to provide an industrially advantageousmethod of producing hydroformylation products from 3-methyl-3-buten-1-olor analogs thereof at fast reaction rate.

Another object of the invention is to provide a method of producing2-hydroxy-4-methyltetrahydropyran from 3-methyl-3-buten-1-ol at fastreaction rate and in high selectivity.

A further object of the invention is to provide a method of producing3-methylpentane-1,5-diol from hydroformylation products from3-methyl-3-buten-1-ol or an analog thereof in high selectivity.

A still further object of the invention is to provide a method ofproducing β-methyl-δ-valerolactone and 3-methylpentane-1,5-diolsimultaneously from 2-hydroxy-4-methyltetrahydropyran, which isobtainable by hydroformylation of 3-methyl-3-buten-1-ol.

Some of the above objects can be achieved by providing a method ofproducing at least one hydroformylation product selected from the groupconsisting of compounds represented by the general formula ##STR1##which comprises reacting a compound of the general formula ##STR2## withcarbon monoxide and hydrogen in the presence of a rhodium compound freefrom modification by a ligand containing an element belonging to thegroup V of the periodic table, wherein, in the above formula (I), R¹ isa hydrogen atom or a hydroxy-protecting group; and in the above formula(II), when R¹ in general formula (I) is a hydrogen atom, R² and R³ incombination represent the group --O-- and R⁴ is a hydroxyl,3-methyl-3-butenoxy, 3-methyl-5-oxopentyloxy ortetrahydro-4-methyl-2H-2-pyranoxy group and, when R¹ in general formula(I) is a hydroxy-protecting group, R² is the R¹ O group and R³ and R⁴combinedly represent the group ═O.

One of the other objects can be accomplished by providing a method ofproducing 3-methylpentane-1,5-diol which comprises hydrogenating theabove hydroformylation product in the presence of water, a hydrogenationcatalyst and an acidic substance.

One of the other objects can be attained by providing a method ofsimultaneously producing β-methyl-δ-valerolactone and3-methylpentane-1,5-diol which comprises reacting one of the abovehydroformylation products, namely 2-hydroxy-4-methyltetrahydropyran in anonoxidating gas atmosphere in the presence of a specificcopper-containing catalyst.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings,

FIG. 1 is an NMR spectrum as obtained withtetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran produced inaccordance with the present invention;

FIG. 2 is an IR spectrum as obtained withtetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran produced inaccordance with the present invention;

FIG. 3 shows an NMR spectrum as obtained with5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal produced inaccordance with the present invention; and

FIG. 4 is an IR spectrum as obtained with5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal produced inaccordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The compound of general formula (I), which serves as a starting materialin the practice of the invention, includes 3-methyl-3-buten-1-ol andanalogs thereof respectively corresponding to the case where R¹ ingeneral formula (I) is a hydrogen atom and the case where R¹ is ahydroxy-protecting group. As said hydroxy-protecting group, there may beused any organic protective group provided that it can substantiallyprotect the hydroxyl group of 3-methyl-3-buten-1-ol against chemicalchanges in the hydroformylation reaction system (to be mentioned later)employed in accordance with the invention. Thus, said hydroxy-protectinggroup includes, among others, such commonly known hydroxy-protectinggroups as straight or branched lower alkyl groups containing 1 to 4carbon atoms, namely methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, sec-butyl and tert-butyl; aryl groups containing 6 to 8 carbonatoms, which may optionally be alkyl- or alkoxy-substituted, for examplephenyl, benzyl and dimethoxyphenyl, and acyl groups containing 2 to 4carbon atoms, for example acetyl, propionyl and butyryl. Anotherfavorable example of the hydroxy-protecting group to be used in thepractice of the invention is tetrahydro-4-methyl-2H-2-pyranyl group.

As the rhodium compound to be used in the practice of the invention,there may be used any rhodium compound capable of catalyzing thehydroformylation or being converted in the hydroformylation reactionsystem to thereby acquire hydroformylation-catalyzing activity, providedthat it remains unmodified by a ligand containing an element belongingto the group V of the periodic table. Said element belonging to thegroup V of the periodic table is, for example, nitrogen, phosphorus,arsenic, or antimony. Examples of the ligand containing such element areorganic tertiary phosphines such as triphenylphosphine andtributylphosphine; organic tertiary phosphites such as triphenylphosphite and tributyl phosphite; organic tertiary arsines such astriphenylarsine and trioctylarsine; and organic tertiary stibines suchas triphenylstibine. Typical examples of the rhodium compound to be usedin the practice of the invention are rhodium chloride; rhodium salts oforganic carboxylic acids such as rhodium acetate and rhodium propionate;rhodium-carbonyl compounds such as Rh₄ (CO)₁₂, Rh₆ (CO)₁₆ and [Rh(CO)₂Cl]₂ ; di-μ-chlorobis(1,3-cyclopentadiene)dirhodium anddi-μ-chlorobis(1,5-cyclooctadiene)dirhodium. Among them particularlypreferred are rhodium-carbonyl compounds,di-μ-chlorobis(1,3-cyclopentadiene)dirhodium anddi-μ-chlorobis(1,5-cyclooctadiene)dirhodium. Metallic rhodium supportedon a carrier such as activated carbon is known to form a catalyticallyactive compound in the hydroformylation reaction system as a result ofcoordination bonding with carbon monoxide (cf. British Pat. No.1,280,707, U.S. Pat. No. 3,527,809, etc.) and such metallic rhodium canalso be used in the practice of the invention. The concentration of therhodium compound in the liquid hydroformylation reaction mixture ispreferably in the range of 0.005 to 5 milligram atom (as rhodium) perliter, more preferably 0.01 to 1 milligram atom (as rhodium) per liter,most preferably 0.02 to 0.5 milligram atom (as rhodium) per liter.

In accordance with the invention, the hydroformylation temperature issuitably within the range of 60° C. to 150° C., preferably 90° C. to120° C. At temperatures below 60° C., the reaction rate is slow,whereas, at temperatures exceeding 150° C., the stability of the rhodiumcompound existing as the catalyst can hardly be maintained. The reactionpressure is generally within the range of 80 to 300 atmospheres(absolute), although it depends on the reaction temperature. The moleratio between the raw material gases at the time of entering thereactor, namely the hydrogen gas/carbon monoxide gas mole ratio, isdesirably within the range of about 3/1 to 1/3. A gas inert to thehydroformylation reaction, such as methane, ethane, propane, nitrogen,helium, argon or carbon dioxide, may coexist in the reaction system. Thehydroformylation reaction may be carried out either in the absence or inthe presence of an organic solvent inert in the reaction system.Examples of such organic solvent are saturated aliphatic hydrocarbonssuch as propane, butane, pentane, hexane, heptane, octane, nonane,decane and octadecane; saturated alicyclic hydrocarbons such ascyclohexane, methylcyclohexane and decaline; aromatic hydrocarbons suchas benzene, toluene, xylene, mesitylene, ethylbenzene and butylbenzene;ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone andcyclohexanone, ethers such as diethyl ether, diisopropyl ether, dibutylether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether,tetrahydrofuran and dioxane; esters such as methyl acetate, ethylacetate, isopropyl acetate, butyl acetate, 2-ethylhexyl acetate, methylpropionate and ethyl propionate; and alcohols such as ethanol, butanol,3-methylbutanol and 3-methylpentane-1,5-diol. Although it depends on thekind and concentration of the rhodium compound used, the reaction timerequired to drive the reaction to a conversion of the starting3-methyl-3-buten-1-ol or an analog thereof which is nearly equal to 100%is generally about 1 to 10 hours. When such conversion is lower than100%, 3-methyl-3-buten-1-ol or an analog thereof remaining unreacted canbe separated from the reaction mixture and again fed as the raw materialfor the hydroformylation reaction.

The rhodium compound can be recovered easily by a variety of methods ifnecessary. Thus, for example, water is added or not added to thereaction mixture after hydroformylation and then the pressure within thesystem is lowered while maintaining the reaction mixture at atemperature within the range of 40° C. to the hydroformylation reactiontemperature, whereby the rhodium compound precipitates out as the metalor a compound thereof. This precipitate (metallic rhodium or the rhodiumcompound) can be recovered by filtration, centrifugation or the liketechnique. It can also be recovered in a simple and easy way bycontacting the reaction mixture with an adsorbent such as activatedcarbon or diatomaceous earth to thereby cause adsorption of the same.The rhodium compound can also be recovered from the reaction mixture inan efficient manner by causing a metal such as aluminum, zinc, chromium,iron, copper or nickel to exist in the reaction mixture and reduce thepressure within the system in the same manner as above to thereby causeprecipitation of the rhodium compound, in the form metallic rhodium orthe compound thereof, on the surface of the above-mentioned metal.Furthermore, it is possible to recovery the precipitate (metallicrhodium or the rhodium compound) from the distillation residue remainingafter distillation of the hydroformylation reaction mixture, for exampleby molecular distillation. The metallic rhodium or compound thereof thusrecovered can be reused as the catalyst for the hydroformylationreaction, if necessary after purification or treatment such as theconversion to the rhodium compound by the conventional method. On thecontrary, when the hydroformylation is carried out in the presence of arhodium compound modified by a ligand containing an element belonging tothe group V of the periodic table, substantial precipitation of saidcompound in the reaction mixture or distillation residue does not occureven when the pressure within the system is lowered in the above mannerfor the purpose of recovering the inactivated rhodium compound, andtherefore the above-mentioned method of separation and recovery cannotbe applied and many difficulties are encountered in efficient separationand recovery of the rhodium compound. Moreover, the recovery of metallicrhodium or the compound thereof is often accompanied by loss or damageof the expensive ligand, typically triphenylphosphine.

The liquid reaction mixture after hydroformylation contains ahydroformylation product consisting of at least one compound selectedfrom the group consisting of compounds having the above-mentionedgeneral formula (II). When the starting material is the compound ofgeneral formula (I) in which R¹ is a hydrogen atom, namely3-methyl-3-buten-1-ol, R² and R³ in general formula (II) combinedlyrepresent the group --O-- and R⁴ is a hydroxyl, 3-methyl-3-butenoxy,3-methyl-5-oxopentyloxy or tetrahydro-4-methyl-2H-2-pyranoxy group. Insuch case, the compound of general formula (II) has the general formula##STR3## wherein R⁵ is a hydroxyl, 3-methyl-3-butenoxy,3-methyl-5-oxopentyloxy or tetrahydro-4-methyl-2H-2-pyranoxy group, and,specifically, is 2-hydroxy-4-methyltetrahydropyran of the formula##STR4## or tetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran of theformula ##STR5## or 5-(tetrahydro-4-methyl-2H-pyranoxy)-3-methylpentanalof the formula ##STR6## or bis(tetrahydro-4-methyl-2H-2-pyranyl) etherof the formula ##STR7## When the starting material is a compound ofgeneral formula (I) in which R¹ is a hydroxy-protecting group, namely ananalog of 3-methyl-3-buten-1-ol, R² in general formula (II) representsthe group R¹ O-- and R³ and R⁴ in general formula (II) combinedlyrepresent the group ═O. In this case, the compound of general formula(II) is an analog of 5-hydroxy-3-methylpentanal having the generalformula ##STR8## wherein R¹ is a hydroxy-protecting group, and is, forexample, 5-acetoxy-3-methylpentanal when R¹ is an acethyl group, or5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal when R¹ is atetrahydro-4-methyl-2H-2-pyranyl group.

As mentioned above, the hydroformylation, when carried out in accordancewith the present invention using 3-methyl-3-buten-1-ol as the startingmaterial, gives a hydroformylation product consisting of at least onecompound selected from compounds of general formula (II'). Theabove-mentioned organic solvent, when coexisting in the hydroformylationreaction system even in a small amount, increases the selectivity toward2-hydroxy-4-methyltetrahydropyran in the hydroformylation. It has beenfound that, for the purpose of obtaining2-hydroxy-4-methyltetrahydropyran as the principal hydroformylationproduct, it is important to cause at least one organic compoundcontaining 3 to 18 carbon atoms, preferably 6 to 10 carbon atoms,selected from the group consisting of saturated aliphatic hydrocarbons,saturated alicyclic hydrocarbons, aromatic hydrocarbons, ketones, ethersand esters to exist in the hydroformylation reaction system as theorganic solvent in an amount of not less than 10% by weight, preferably10 to 80% by weight, more preferably 15 to 50% by weight, based on theweight of the reaction mixture. Typical examples of such organiccompound containing 3 to 18 carbon atoms are saturated aliphatichydrocarbons such as propane, butane, pentane, hexane, heptane, octane,nonane, decane and octadecane; saturated alicyclic hydrocarbons such ascyclohexane, methylcyclohexane and decalin; aromatic hydrocarbons suchas benzene, toluene, xylene, mesitylene, ethylbenzene and butylbenzene;ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone andcyclohexanone; ethers such as diethyl ether, diisopropyl ether, dibutylether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether,tetrahydorfuran and dioxane; and esters such as methyl acetate, ethylacetate, isopropyl acetate, butyl acetate, 2-ethylhexyl acetate, methylpropionate and ethyl propionate. These organic compounds may be usedeither alone or in combination of two or more. Among these particularlypreferred from the viewpoints of stability in the reaction mixture andcost are saturated aliphatic hydrocarbons, saturated alicyclichydrocarbons and aromatic hydrocarbons. To increase the amount of theorganic solvent with the increase in rhodium compound concentrationand/or reaction temperature generally tends to give favorable results.With the increase in the amount of such organic solvent in the reactionmixture, the selectivity toward 2-hydroxy-4-methyltetrahydropyranincreases and, when said amount is not less than 10% by weight, theselectivity toward 2-hydroxy-4-methyltetrahydropyran is at a level whichis practical for obtaining said compound as the objective compound. Whensaid amount is not less than 15% by weight, said selectivity becomesmarkedly high. When the organic solvent is present in an amountexceeding 50% by weight, the above selectivity remains at a high levelbut further increase in the amount of the organic solvent generallybrings about no further corresponding increase in said selectivity anymore. When the organic solvent is present in an amount exceeding 80% byweight, then the reaction rate becomes slow and at the same time thevolume of the organic solvent to be recovered after the hydroformylationreaction increases, which is unfavorable from the industrial viewpoint.

In carrying out the hydroformylation in the presence of an organicsolvent, the conversion of 3-methyl-3-buten-1-ol is not critical.However, in some cases, driving the reaction to an extent such that theconversion of 3-methyl-3-buten-1-ol reaches almost 100% may result inconversion of 2-hydroxy-4-methyltetrahydropyran once formed to anundesired compound as a result of acetalization and so on, leading to adecrease in the selectivity toward 2-hydroxy-4-methyltetrahydropyran.When the conversion of 3-methyl-3-buten-1-ol is lower than 100%, theunreacted 3-methyl-3-buten-1-ol can be separated from the reactionmixture obtained and thereafter used for the hydroformylation reactionas the raw material. However, when the conversion of3-methyl-3-buten-1-ol is too low, a large amount of unreacted3-methyl-3-buten-1-ol must be separated and recovered from the liquidreaction mixture, which is not practical. Therefore, for the purpose ofproducing 2-hydroxy-4-methyltetrahydropyran in a particularly highselectivity and in an industrially advantageous manner, it is preferredthat the conversion of 3-methyl-3-buten-1-ol is within the range ofabout 20 to 97%, more preferably about 50 to 95%.

The reaction mixture obtained by the hydroformylation reaction in thepresence of an organic solvent contains, in addition to2-hydroxy-4-methyltetrahydropyran, small amounts of otherhydroformylation products except for the organic solvent and unreacted3-methyl-3-buten-1-ol. After processing for the separation and recoveryof the rhodium compound by the above-mentioned method as necessary, theprincipal product 2-hydroxy-4-methyltetrahydropyran can be separatedfrom the liquid reaction mixture easily by subjecting the liquidreaction mixture to such separation procedure as distillation orextraction.

When 3-methyl-3-buten-1-ol is used as the starting material, the use ofa specific organic solvent and specific reaction conditions andtreatment conditions in the hydroformylation according to the presentinvention also makes it possible to separate the rhodium compound fromthe liquid hydroformylation reaction mixture without any substantialdecrease in catalytic activity and recycle and reuse the same in thehydroformylation. It has been found that this purpose can be achieved byproviding a method of producing hydroformylation products whichcomprises reacting 3-methyl-3-buten-1-ol with hydrogen and carbonmonoxide in an organic solvent consisting essentially of a saturatedaliphatic hydrocarbon and/or a saturated alicyclic hydrocarbon which mayoptionally contain not more than 35% by weight of an aromatichydrocarbon in the presence of a rhodium compound free from modificationby a ligand containing an element belonging to the group V of theperiodic table in a concentration of 0.01 to 0.5 milligram atom (asrhodium atom) per liter at a temperature within the range of 60° to 150°C. and a pressure within the ragne of 80 to 300 atmospheres (absolute),extracting the liquid hydroformylation reaction mixture obtained withwater in a mixed gas atmosphere composed of hydrogen and carbon monoxideto thereby extract the hydroformylation product into the aqueous layerto an extent such that the concentration of2-hydroxy-4-methyltetrahydropyran in the aqueous layer amounts to notmore than 2 moles/liter, and recycling the extraction residue containingthe rhodium compound to the hydroformylation reaction zone.

In the production method using this extractive separation, the use, asthe organic solvent in the hydroformylation reaction, of a mixed solventcomposed of a saturated aliphatic hydrocarbon and/or a saturatedalicyclic hydrocarbon and an aromatic hydrocarbon in which the aromatichydrocarbon accounts for more than 35% by weight of the whole organicsolvent leads to worsened separability of the extraction interface anddecreased extractability in the extraction step following the reaction.The concentration of the rhodium compound in the liquid reaction mixtureis required to be adjusted such that the rhodium atom concentrationamounts to 0.01 to 0.5 milligram atom per liter, preferably 0.02 to 0.2milligram atom per liter. When such concentration is lower than 0.01milligram atom per liter, the hydroformylation reaction is slow and,when it exceeds 0.5 milligram atom per liter, the dissolution of therhodium compound into the extractant water layer increases in the stepof extraction of the liquid reaction mixture. A rhodium concentrationoutside the above range is thus disadvantageous from the industrialviewpoint. In the above method, an organic solvent is caused to exist inthe hydroformylation reaction system, so that the selectivity toward2-hydroxy-4-methyltetrahydropyran in the hydroformylation reaction ishigh and in most cases 2-hydroxy-4-methyltetrahydropyran is theprincipal component of said hydroformylation product. However, it ispreferred that the amount of the organic solvent, the feed rate of3-methyl-3-buten-1-ol and the residence time of the liquid reactionmixture in the reactor are selected so that the concentration of2-hydroxy-4-methyltetrahydropyran in the liquid reaction mixture afterhydroformylation can amount to about 0.5 to 5 moles per liter.

It is necessary to adjust the amount of water to be added to the liquidreaction mixture in the step of extraction of the hydroformylationproduct following the hydroformylation reaction such that theconcentration of 2-hydroxy-4-methyltetrahydropyran in the aqueous layerafter extraction is not more than 2 moles per liter, preferably 0.5 to1.5 moles per liter. The volume of water which meets this requirementvaries to some extent depending on the concentration of2-hydroxy-4-methyltetrahydropyran in the liquid reaction mixture to besubjected to extraction, for instance, but is generally within the rangeof about 0.5 to 3 volumes per volume of the liquid reaction mixture tobe subjected to extraction. An increased concentration of2-hydroxy-4-methyltetrahydropyran in the extractant aqueous layer isaccompanied by an increased dissolution of the rhodium compound in theaqueous layer. It is essential that the extraction procedure should becarried out in a mixed gas atmosphere composed of hydrogen and carbonmonoxide so that the deposition of the rhodium compound in the liquidreaction mixture can be prevented. The hydrogen-carbon monoxide mixedgas may have the same composition as that of the raw material gas to beused in the hydroformylation reaction, and the hydrogen/carbon monoxidemole ratio is preferably within the range of about 1/3 to 3/1. Theextraction procedure is preferably performed at a temperature within therange of about 0° to 50° C., more preferably about 10° to 30° C. Thepressure is preferably within the range of about 1 to 300 atmospheres(absolute), more preferably about 2 to 100 atmospheres (absolute). Asthe extraction apparatus, there may be used, for example, anagitated-column extractor (mixer settler, rotary disc contactor, etc.)or plate column extractor (perforated plate column, etc.), which is ingeneral and common use. In this method, the extraction residuecontaining the rhodium compound after the extraction step is recycledfor reuse to the hydroformylation reaction zone. Part of the liquidreaction mixture after hydroformylation or of the extraction residue maybe taken out for treatment, such as catalyst activation, as necessary.It is also possible to recover the rhodium compound from the liquidreaction mixture or extraction residue taken out, by the above-mentionedmethod of separation and recovery.

The hydroformylation product such as 2-hydroxy-4-methytetrahydropyrancan be isolated from the aqueous extract containing the hydroformylationproduct obtained by the above extraction procedure, by such separationtechnique as distillation or extraction. In particular, thehydroformylation product can be isolated efficiently by reextracting theaqueous extract containing the hydroformylation product with a specificorganic extractant. Such organic extractant is a substantiallywater-soluble one and is selected from among esters such as isopropylacetate, butyl acetate, isobutyl acetate, isoamyl acetate and methylpropionate; ketones such as methyl isobutyl ketone and dibutyl ketone;aromatic hydrocarbons such as benzene and toluene; and3-methyl-3-buten-1-ol. These are used either alone or in admixture oftwo or more. The organic extractant is used generally in an amount ofabout 0.2 to 3 volumes pe volume of the aqueous solution containing thehydroformylation product. When the amount of the organic extractant isless than about 0.2 volume per volume of the aqueous solution, a fairlylarge amount of the hydroformylation product remains in the aqueousextraction residue solution, whereby the extraction cannot be efficientin some instances. The use of larger amount of organic extractant tendsto increase the transfer of the hydroformylation product from theaqueous solution to the organic extractant but, when the amount oforganic extractant exceeds about 3 volumes per volume of the aqueoussolution, further increase in the amount of organic extractant will notproduce further increase in the transfer of the hydroformylation productinto the organic extractant any more and will result in the mere use ofan unduly large amount of organic extractant. The extraction temperatureis not critical but is preferably within the range of about 0° to 100°C. The atmosphere to be used in the extraction procedure is not criticalunless adversely affecting the hydroformylation reaction. However, it ispreferable to perform the extraction procedure in a hydrogen-carbonmonoxide mixed gas or a gas inert to the hydroformylation reaction, suchas methane, ethane, propane, nitrogen, helium, argon or carbon dioxide,more preferably in a hydrogen-carbon monoxide mixed gas atmosphere. Asthe pressure during extraction, there may be applied a pressuregenerally used in ordinary extraction procedures, and a pressure in theneighborhood of atmospheric pressure is in general advantageous.

The hydroformylation product such as 2-hydroxy-4-methyltetrahydropyrancan be isolated by subjecting the organic layer obtained by reextractionto separation procedure such as distillation. The separation of thehydroformylation product from the organic solution by distillationrequires less heat energy as compared with the separation of thehydroformylation product from an aqueous solution and thereforeadvantageous from the industrial viewpoint. In some instances, a smallamount of hydroformylation product may remain dissolved in theextraction residue aqueous solution obtained in the reextraction.Therefore, it is preferable to recycle for reuse the extraction residueaqueous solution to the above-mentioned zone where the hydroformylationproduct are extracted with water.

As regards the hydroformylation of 3-methyl-3-buten-1-ol and analogsthereof, it is known in the art that 3-methyl-3-buten-1-ol can behydroformylated in the presence of a rhodium compound modified by anorganic tertiary phosphine. As compared with such prior art method, themethod of the present invention according to which the hydroformylationof 3-methyl-3-buten-1-ol or analogs thereof is carried out in thepresence of a rhodium compound free from modification by a ligandcontaining an element belonging to the group V of the periodic tablegives the hydroformylation product at a much faster reaction rate. Inaccordance with the invention, it is also possible to separate andrecover the rhodium compound used in the hydroformylation step from thehydroformylation reaction mixture in a simple and easy manner or toseparate said compound from the hydroformylation reaction mixture whilemaintaining its catalitic activity and recycle for reuse to thehydroformylation step. In accordance with the present invention, it isfurther possible to obtain 2-hydroxy-4-methyltetrahydropyran at a fastreaction rate and in high selectivity by selecting the hydroformylationconditions.

The 2-hydroxy-4-methyltetrahydropyran obtained in accordance with thepresent invention can easily be converted to β-methyl-δ-valerolactone bydehydrogenating in the presence of an oxidative dehydrogenation catalystsuch as copper chromite. Furthermore, 2-hydroxy-4-methyltetrahydropyrancan be easily converted to 3-methylpentane-1,5-diol by hydrogenating inthe presence of a hydrogenation catalyst such as Raney nickel,nickel-on-diatomaceous earth or copper chromite.

In accordance with the present invention, there can be obtained, as thehydroformylation product from 3-methyl-3-buten-1-ol, the followingcompounds, either alone or in the form of a mixture of two or more:2-hydroxy-4-methyltetrahydropyran,tetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran,5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal andbis(tetrahydro-4-methyl-2H-2-pyranyl)ether. The components other than2-hydroxy-4-methyltetrahydropyran can be converted to2-hydroxy-4-methyltetrahydropyran by subjecting to hydrolysis.Accordingly, in cases where 2-hydroxy-4-methyltetrahydropyran is to beproduced by hydrolyzing the hydroformylation products obtained, there isno need of isolating the respective components in the hydroformylationproduct in advance.

In accordance with the present invention, it is also possible to obtain,in addition to the above-mentioned compounds, various5-hydroxy-3-methylpentanal analogs in high yields as thehydroformylation product from 3-methyl-3-buten-1-ol analogs. Such5-hydroxy-3-methyl-pentanal analogs can be converted to2-hydroxy-4-methyltetrahydropyran by such treatment as hydrolysis and isuseful as an intermediate for the synthesis of drugs and perfumes, forinstance.

The hydroformylation product obtained in accordance with the presentinvention can be converted to 3-methylpentane-1,5-diol in one reactionstep as will be mentioned later herein.

Furthermore, the 2-hydroxy-4-methyltetrahydropyran obtained inaccordance with the present invention can be used as an intermediate forthe simultaneous parallel production of β-methyl-δ-valerolactone and3-methylpentane-1,5-diol by the method to be mentioned later herein.

Production of 3-methylpentane-1,5-diol:

3-Methylpentane-1,5-diol can be produced by hydrogenating, in thepresence of water, a hydrogenation catalyst and an acidic substance, thehydroformylation product obtained by the method according to the presentinvention from a compound of the general formula ##STR9## wherein R⁶ isa hydrogen atom or a tetrahydro-4-methyl-2H-2-pyranyl group, namely3-methyl-3-buten-1-ol ortetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran.

The hydroformylation product to be subjected to hydrogenation is ahydroformylation product consisting of one compound or a mixture of twoor more compounds selected from the group consisting of the compounds ofthe above formula (II') as obtained from 3-methyl-3-buten-1-ol or ahydroformylation product consisting of5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal obtained fromtetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran. In carrying outthe hydrogenation, such hydroformylation product can be used as it is,without isolation of each component, as the raw material for thehydrogenation reaction.

Examples of the hydrogenation catalyst, which are usable in the abovehydrogenation reaction, are various hydrogenation catalysts such asRaney nickel, Raney cobalt, palladium black, copper chromite and nickel,ruthenium, cobalt, palladium or copper chromite supported on a carriersuch as diatomaceous earth, alumina or carbon. Particularly preferredare nickel catalysts. These catalysts may be partly modified withchromium, molybdenum, manganese, tungsten, etc. The use of ahydrogenation catalyst treated in advance with a carboxylic acid such asacetic acid or propionic acid is very favorable from the viewpoint ofthe presence of an acidic substance in the hydrogenation reactionsystem.

As the solvent in carrying out the hydrogenation, there may be usedwater either alone or in combination with an optionally selected organicsolvent incapable of adversely affecting the hydrogenation reaction.Preferred as said organic solvent are those organic solvents which areat least partially soluble in water, such as lower alcohols, e.g.methanol, ethanol, propanol, butanol and isoamyl alcohol;3-methylpentane-1,5-diol; and ethers, e.g. tetrahydrofuran and dioxane.However, hydrocarbons such as hexane, cyclohexane, benzene and toluenemay also be used.

Water is required to be present in the hydrogenation reaction system sothat hydroformylation product compounds other than2-hydroxy-4-methyltetrahydropyran can be hydrolyzed. The amount of watercan be selected arbitrarily in not less than the stoichiometricallyrequired amount. Whether an organic solvent is used or not, it is ingeneral preferred that water be present in the hydrogenation reactionmixture in an amount of not less than about 0.05 part by weight, morepreferably within the range of about 0.1 to 5 parts by weight, per partby weight of the hydroformylation product.

The hydrogenation is performed in the presence of an acidic substance.The term "acidic substance" as used herein includes, among others, solidacids, such as cation exchange resins, silica-alumina, silica, aluminaand diatomaceous earth; organic acids, such as acetic acid, propionicacid, isovaleric acid and benzoic acid; and inorganic acids, such asphosphoric acid, boric acid, hydrochloric acid and sulfuric acid.However, organic acids are preferred. Said solid acids may also serve asthe carriers for the above-mentioned hydrogenation catalysts. When theorganic or inorganic acid is employed as the acidic substance, it isnecessary that such organic or inorganic acid should be present in thereaction mixture in an amount sufficient to render the reaction mixtureacidic, preferably in an amount sufficient to acidify the reactionmixture to a pH within the range of 1 to 5.5, more preferably 3 to 5.When the reaction mixture has a pH lower than 1, the hydrogenationcatalyst decreases in catalyst activity due to partial dissolutionthereof in the solution. When the pH is higher than 5.5, the rate ofreaction or yield of 3-methylpentane- 1,5-diol decreases. The case inwhich the hydrogenation of the hydroformylation product is carried outin the presence of water and a hydrogenation catalyst under acidicconditions of course fall within the scope of the above hydrogenationmethod. When the solid acid is employed, the solid acid concentration tobe attained in the reaction mixture is generally within the range of0.05 to 10% by weight based on the weight of the reaction mixturealthough said concentration depends on the acid strength of the solidacid and the number of acid sites therein. It is preferable to cause theabove acidic substance, such as a solid acid, organic acid or inorganicacid, to be present in the reaction mixture from the beginning of thehydrogenation step. However, it is also possible to add said acidicsubstance to the reaction mixture in the course of the hydrogenationreaction.

The hydrogenation can be carried out using either a fixed bed or asuspended bed. The hydrogenation reaction temperature is generallywithin the range of 50° to 250° C., preferably 80° to 200° C., mostpreferably 70° to 150° C. The hydrogen pressure in the reaction systemdepends on the kind of hydrogenation catalyst employed but is generallywithin the range of 2 to 200 atmospheres (absolute), preferably 5 to 150atmospheres (absolute), most preferably 10 to 100 atmospheres(absolute), for the cases where nickel catalysts, such as Raney nickeland nickel-on-diatomaceous earth; cobalt catalysts, such as Raney cobaltand cobalt-on-diatomaceous earth; and palladium catalysts, such aspalladium black and palladium-on-carbon, are used as the hydrogenationcatalysts, or generally within the range of 50 to 300 atmospheres(absolute), preferably 100 to 250 atmospheres (absolute), for the caseswhere copper catalysts, such as copper chromite, are used as thehydrogenation catalysts.

The hydrogenation product obtained by the above hydrogenation contains3-methylpentane-1,5-diol as the main component thereof and alsocontains, in some instances, small amounts of by-products such asisoamyl alcohol. The desired 3-methylpentane-1,5-diol can be isolatedfrom the reaction mixture after hydrogenation by an optionally selectedseparation procedure such as fractional distillation following theremoval of the hydrogenation catalyst, acidic substance, water, and thesolvent used (if any).

The application of this hydrogenation to the hydroformylation productfrom tetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran isparticularly favorable for the purpose of markedly increasing theselectivity toward 3-methylpentane-1,5-diol while inhibiting theformation of by-product isoamyl alcohol.

Tetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran can be produced inalmost quantitative yield, for example by dehydration-condensation of2-hydroxy-4-methyltetrahydropyran with 3-methyl-3-buten-1-ol in thepresence of an acid catalyst (method 1), by subjecting an2-alkoxy-tetrahydro-4-methyl-2H-pyran of the general formula ##STR10##wherein R⁷ is a lower alkyl group containing not more than 4 carbonatoms, and 3-methyl-3-buten-1-ol to acetal exchange in the presence ofan acid catalyst (method 2), or by reacting5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal with3-methyl-3-buten-1-ol in the presence of an acid catalyst (method 3).The reaction involved in method 3 is given by the following reactionequation, 1 mole of5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal yielding 2 molesof tetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran: ##STR11##

The acid catalyst to be used in the above methods 1-3 may be either aprotonic acid or a Lewis acid. The protonic acid includes, among others,organic carboxylic acids such as acetic acid, propionic acid,2-ethylhexanoic acid, benzoic acid and terephthalic acid; organicsulfonic acids such as benzenesulfonic acid and p-toluenesulfonic acid;acidic macromolecular compounds such as cation exchange resins andphenolic resins; and inorganic protonic acids such as sulfuric acid,hydrochloric acid, phosphoric acid, sodium hydrogensulfate and sodiumdihydrogenphosphate, whereas the Lewis acid includes copper sulfate,nickel chloride, calcium chloride, ferric chloride, zinc chloride,alumina, silica alumina, active clay, etc. Among these, particularlypreferred from the viewpoint of easy separation of the catalyst aresolid acids such as cation exchange resins and silica alumina. Theamount of the acid catalyst is not particularly critical but generallywithin the range of 0.01 to 10% by weight based on the weight of thereactant. The quantitative ratio of 2-hydroxy-4-methyltetrahydropyran,2-alkoxytetrahydro-4-methyl-2H-pyran or5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal to3-methyl-3-buten-1-ol is preferably equal or close to the stoichiometricone. Thus, it is preferable to react about 0.7 to 1.2 moles of2-hydroxy-4-methyltetrahydropyran (in method 1), about 0.7 to 1.2 molesof 2-alkoxy-tetrahydro-4-methyl-2H-pyran (in method 2) or about 0.4 to0.55 mole of 5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal (inmethod 3) with one mole of 3-methyl-3-buten-1-ol. However, suchquantitative ratio is not limited to the above-mentioned one. Forexample, 3-methyl-3-buten-1-ol may be used in excess. The reactiontemperature is generally within the range of 0° to 150° C., preferably20° to 100° C. In carrying out the above methods, it is not alwaysnecessary that a solvent be present in the reaction system. However, anoptionally selected solvent may be used provided that the reaction isnot adversely affected thereby. Usable solvents are saturated aliphatichydrocarbons such as hexane, heptane and octane; saturated alicyclichydrocarbons such as cyclohexane and methylcyclohexane; aromatichydrocarbons such as benzene, toluene and xylene; halogenatedhydrocarbons such as methylene chloride, chloroform, carbontetrachloride and dichloroethane; ethers such as diethyl ether,tetrahydrofuran, dioxane and diethylene glycol dimethyl ether; andketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone.It is particularly preferable to use a saturated aliphatic hydrocarbon,saturated alicyclic hydrocarbon or aromatic hydrocarbon and conduct thereaction while removing water or lower alcohol, which is formed, fromthe reaction system. The amount of the solvent is not critical but, fromthe viewpoint of the solvent recovery, it is in general suitable to usenot more than 20 parts by weight of solvent per part by weight ofreactants.

When the above method 3 is combined with the production of3-methylpentane-1,5-diol by hydrogenation of the hydroformylationproduct from tetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran andpart of 5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal, which isthe hydroformylation product fromtetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran, is used for theproduction of tetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran withthe remaining portion of said hydroformylation product being directed tothe production of 3-methylpentane-1,5-diol, the resulting productionprocess involves the following three reactions:

(i) Formation of 5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanalby the hydroformylation oftetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran; ##STR12##

(ii) Formation of 3-methylpentane-1,5-diol by the hydrogenation of5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal; ##STR13## and

(iii) Formation of tetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyranby the acetal exchange between5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal and3-methyl-3-buten-1-ol: ##STR14##

As the result of the combination of these reactions,3-methylpentane-1,5-diol can be produced from 3-methyl-3-buten-1-ol,carbon monoxide and hydrogen, as shown by the reaction equation givenbelow: ##STR15##

Tetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran and5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal are novelcompounds which have not yet been described in the literature, and theyare important intermediates in synthesizing 3-methylpentane-1,5-diolfrom 3-methyl-3-buten-1-ol by the above-mentioned process.

Simultaneous production of β-methyl-δ-valerolactone and3-methylpentane-1,5-diol:

β-Methyl-δ-valerolactone and 3-methylpentane-1,5-diol can be producedsimultaneously by reacting 2-hydroxy-4-methyltetrahydropyran at atemperature of 110° to 190° C. in a nonoxidizing gas atmosphere in thepresence of a catalyst containing a mixed oxide of copper and at leastone metal selected from the group consisting of chromium and zinc.

Said 2-hydroxy-4-methyltetrahydropyran to be used in the abovesimultaneous production can be produced from 3-methyl-3-buten-1-ol bythe above-mentioned hydroformylation according to the present invention.Such hydroformylation is preferably carried out in the presence of anorganic solvent to thereby increase the selectivity toward2-hydroxy-4-methyltetrahydropyran, as mentioned hereinbefore.Specifically, the catalyst to be used in said simultaneous productioncontains copper chromite, copper-chromium oxide, copper-zinc oxide orcopper-chromium-zinc oxide as the main effective catalyst component. Theeffective catalyst component may be used either alone as it is or in theform supported on a carrier such as alumina, silica or diatomaceousearth. Catalysts of this kind are commercially produced and readilyavailable and, moreover, can be prepared by the methods described, forexample, in Organic Synthesis, Coll. Vol. II, 142 (1943); J. Am. Chem.Soc., 54, 1138 (1932); J. Am. Chem. Soc., 58, 1053 (1936); Ind. Eng.Chem., 27, 134 (1935); and Ind. Eng. Chem., 21, 1052 (1929). Thecatalyst may be partly modified with other metal, such as a metalselected from tungsten, molybdenum, rhenium, zirconium, manganese,titanium, iron, barium, magnesium, calcium, etc., or a compound thereof.Some catalysts may be improved in catalytic activity by treatment withhydrogen prior to use. Such catalysts are generally used singly,although they may of course be used in combination of two or more. Thereaction involved in this simultaneous production method is carried outin the liquid phase using either a suspended bed or fixed bed.

Said reaction is conducted at a reaction temperature within the range of110° to 190° C., preferably 130° to 180° C. At a reaction temperaturebelow 110° C., the reaction rate is slow or the reaction does notprogress to a substantial extent. At a temperature higher than 190° C.,the formation of 3-methylpentane-1,5-diol is inhibited, whereby it isvery difficult in some cases to obtain 3-methylpentane-1,5-diol in asatisfactory yield.

The reaction for said simultaneous production is performed in anonoxidizing gas atmosphere to thereby avoid oxidation of the rawmaterial and of the product. Typical and preferred nonoxidizing gasesare inert gases such as nitrogen, helium and argon, and hydrogen gas.These nonoxidizing gases may be used either singly or in admixture oftwo or more. Among them, nitrogen gas or hydrogen gas is preferablyused. Since the reaction involved in this simultaneous productionprocess can give β-methyl-δ-valerolactone and 3-methylpentane-1,5-diolsimultaneously in a β-methyl-δvalerolactone/3-methylpentane-1,5-diolmole ratio of not less than 1/1 even in a nonoxidizing gas atmosphereother than hydrogen, it is assumed that2-hydroxy-4-methyltetrahydropyran undergoes dehydrogenation on thesurface of the effective catalyst component, givingβ-methyl-δ-valerolactone and hydrogen and that this hydrogen theneffectively reacts with 2-hydroxy-4-methyltetrahydropyran to give3-methylpentane-1,5-diol. In a hydrogen gas atmosphere or in a mixed gasatmosphere composed of hydrogen gas and another nonoxidizing gas, theformation of 3-methylpentane-1,5-diol is further promoted and, when thereaction conditions are adequately selected, β-methyl-δ-valerolactoneand 3-methylpentane-1,5-diol can be produced in aβ-methyl-δ-valerolactone/3-methylpentane-1,5-diol mole ratio of not only1/1 or more but also less than 1/1. The reaction pressure is preferablyat least 0.01 atmosphere (absolute) and lower than 20 atmospheres(absolute). When the pressure is 20 atmospheres (absolute) or higher,the formation of β-methyl-δ-valerolactone is inhibited, so that, in someinstances, β-methyl-δ-valerolactone can hardly be obtained in asatisfactory yield. At a pressure lower than 0.01 atmosphere (absolute),the formation of 3-methylpentane-1,5-diol is inhibited, whereby it isdifficult in some instances to obtain 3-methylpentane-1,5-diol in asatisfactory yield.

Whereas, in this reaction, the starting material2-hydroxy-4-methyltetrahydropyran and/or the productsβ-methyl-δ-valerolactone and 3-methylpentane-1,5-diol may serve as thesolvent, it is also possible to use some other organic solvent. Anyorganic solvent can be used provided that it is inert to the reactionand 2-hydroxy-4-methyltetrahydropyran, β-methyl-δ-valerolactone and3-methylpentane-1,5-diol are soluble therein. More specifically, theremay be mentioned, for example, saturated aliphatic hydrocarbons,aromatic hydrocarbons, ethers and esters, such as liquid paraffin,hexane, benzene, toluene, biphenyl, diethylene glycol dimethyl ether,triethylene glycol dimethyl ether and dioctyl phthalate. In solventselection, the intended reaction temperature and pressure as well as theboiling point difference from 2-hydroxy-4-methyltetrahydropyran,β-methyl-δ-valerolactone and 3-methylpentane-1,5-diol should of coursebe taken into consideration.

The reaction may be conducted either batchwise or continuously, althoughcontinuous feeding of 2-hydroxy-4-methyltetrahydropyran to the reactionzone is preferred. After catalyst separation, β-methyl-δ-valerolactone,3-methylpentane-1,5-diol and possibly existing unreacted2-hydroxy-4-methyltetrahydropyran can readily be isolated by aconventional procedure, for example by distillation.

According to the prior art methods, production ofβ-methyl-δ-valerolactone and 3-methylpentane-1,5-diol requiresrespective independent production facilities. On the contrary, thesimultaneous production method can produce β-methyl-δ-valerolactone and3-methylpentane-1,5-diol simultaneously from2-hydroxy-4-methyltetrahydropyran with a common reactor and underrelatively mild conditions. According to this simultaneous productionthereof, β-methyl-δ-valerolactone and 3-methylpentane-1,5-diol areproduced generally in aβ-methyl-δ-valerolactone/3-methylpentane-1,5-diol mole ratio of about70/30 to 15/85. Said simultaneous production method can giveβ-methyl-δ-valerolactone and 3-methylpentane-1,5-diol each in asatisfactory yield and in a yield ratio therebetween selected dependingon the demands therefor.

Having generally described this invention, a further understanding canbe obtained by reference to certain specific examples which are providedherein for purpose of illustration only and are not intended to belimiting unless otherwise specified.

EXAMPLE 1 (a) Production oftetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran

A 300-ml three-necked flask equipped with condensor, stirrer andthermometer was charged with 70 g (0.60 mole) of2-hydroxy-4-methyltetrahydropgran, 52.46 g (0.61 mole) of3-methyl-3-buten-1-ol, 150 ml of hexane and 3 g of active clay, and themixture was stirred at 60° C. for 1 hour. Thereafter, the reactionmixture was analyzed by gas chromatography. The chromatogram showed nopeak for 2-hydroxy-4-methyltetrahydropyran but showed a new peak. Theactive clay was filtered off from the reaction mixture, then, the hexanewas distilled off and the residue was distilled under reduced pressureto give 105 g (98% yield) oftetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran as a fractionboiling at 89.5°-90.0° C./10 mm Hg. A nuclear magnetic resonance (NMR)spectrum (in CDCl₃) and an infrared absorption spectrum (liquidfilm-NaCl method) each obtained with the above product are shown in FIG.1 and FIG. 2, respectively. The NMR spectrum suggested this product wasa mixture of 70% of ##STR16## and 30% of ##STR17## Field desorptionionization (FD) mass spectrometry of this product gave M⁺ =184.

(b) Hydroformylation oftetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran

A 300-ml stainless steel autoclave equipped with a magnetic stirrer wascharged with 80 g of the abovetetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran, 80 ml of hexaneand 0.83 mg of Rh₄ (CO)₁₂. The system was purged thoroughly with a mixedgas composed of hydrogen and carbon monoxide in a mole ratio of 1:1 and,then, the pressure within the system was maintained at 200 atmospheres(absolute) with the same mixed gas. The reaction mixture was heated to100° C. over 30 minutes with stirring and then maintained at 100° C.with stirring for 5 hours. The pressure within the system was maintainedat 200 atmospheres (absolute) throughout the reaction period while theoff-gas was continuously drawn out at a rate of about 5 liters/hr. Aftercompletion of the reaction, the system was returned to ordinarytemperature and pressure, and the reaction mixture was taken out andanalyzed by gas chromatography. The conversion oftetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran was 99.0%. Thehexane was distilled off from the hydroformylation reaction mixture andthe residue was distilled under reduced pressure to give 81 g of5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal as a fractionhaving a boiling point of 113°-114° C./4 mm Hg. A nuclear magneticresonance (NMR) spectrum (in CDCl₃) and an infrared absorption spectrum(liquid film-NaCl method) each obtained with the above product are shownin FIG. 3 and FIG. 4, respectively. Field desorption ionization (FD)mass spectrometry of this product gave M⁺ =214.

COMPARATIVE EXAMPLE 1

Hydroformylation of tetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyranwas carried out in the same manner as Example 1 except that 80 ml oftoluene was used in place of hexane of Example 1 (b) and 300 mg (1.15millimoles) of triphenylphosphine was added to the reaction system.After completion of the reaction, the system was returned to ordinarypressure, whereupon the rhodium compound in the reaction mixture did notprecipitate out, hence rhodium separation by filtration was impossible.Analysis of this reaction mixture by gas chromatography indicated thatthe conversion of tetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyranwas as low as 23% and the selectivity toward5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal was 92%.

EXAMPLE 2

A 1-liter stainless autoclave equipped with a magnetic stirrer wascharged with 516 g (6.00 moles) of 3-methyl-3-buten-1-ol and, as therhodium compound, 11.7 mg (0.0625 milligram atom on the rhodium atombasis) of Rh₄ (CO)₁₂ in an atmosphere of a carbon monoxide-hydrogenmixed gas (mole ratio=1:1), and the atmosphere within the autoclave wasthoroughly substituted with a caron monoxide-hydrogen mixed gas (moleratio=1:1). Thereafter, while maintaining the pressure within theautoclave at 200 atmospheres (absolute) with the same mixed gas, thehydroformylation reaction was conducted for 5 hours at 100° C. withstirring. Throughout the reaction period, the carbon monoxide-hydrogenmixed gas (mole ratio=1:1) was continuously fed into the autoclavethrough a pressure controller to maintain the pressure within the systemat 200 atmospheres (absolute) while the effluent gas flow rate from theautoclave was adjusted at about 5 liters/hr. The reaction mixture wastransferred with the aid of pressure to a 2-liter autoclave which hadbeen previously purged with nitrogen gas, and the mixture was stirred at100° C. under nitrogen gas at 20 atmospheres (absolute) for 30 minutes.After cooling and depressurizing, the metallic rhodium precipitate wasfiltered off from the contents obtained. In this way, 95% of the rhodiumcompound used was recovered in the form of metallic rhodium. Thereaction mixture (675 g) after removal of the metallic rhodiumprecipitate was analyzed by gas chromatography. The unreacted3-methyl-3-buten-1-ol amounted to 0.01 mole (conversion of3-methyl-3-buten-1-ol, 99.8%) and the yield of2-hydroxy-4-methyltetrahydropyran was 2.0 moles (selectivity based on3-methyl-3-buten-1-ol charged, 33%). Other main products were 1.39 moles(selectivity 46.2%) of bis(tetrahydro-4-methyl-2H-2-pyranyl) ether, 0.12mole (selectivity 4.0%) oftetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran, 0.06 mole(selectivity 2.0%) of5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal, 0.18 mole(selectivity 6.0%) oftetrahydro-2-(3-methyl-2-butenoxy)-4-methyl-2H-pyran, 0.43 mole(selectivity 7.2%) of isovaleraldehyde and 0.04 mole (selectivity 0.7%)of 3-methyl-2-buten-1-ol.

EXAMPLE 3

Hydroformylation of 3-methyl-3-buten-1-ol (516 g, 6.00 moles) wascarried out in the same manner as Example 2 except that 15.4 mg (0.0624milligram atom on the rhodium atom basis) ofdi-μ-chlorobis(1,5-cyclooctadiene)dirhodium was used as the rhodiumcompound. The metallic rhodium precipitate was collected by filtrationfrom the contents obtained, whereby 96% of the rhodium used wasrecovered. Analysis of the reaction mixture (670 g) by gaschromatography indicated that the mixture contained 0.04 mole(conversion of 3-methyl-3-buten-1-ol, 99.3%) of 3-methyl-3-buten-1-ol,1.8 moles (selectivity 30%) of 2-hydroxy-4-methyltetrahydropyran, andfurther, 1.4 moles (selectivity 46.7%) ofbis(tetrahydro-4-methyl-2H-2-pyranyl) ether, 0.12 mole (selectivity4.0%) of tetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran, 0.06 mole(selectivity 2.0%) of5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal and 0.20 mole(selectivity 6.7%) oftetrahydro-2-(3-methyl-2-butenoxy)-4-methyl-2H-pyran.

EXAMPLE 4

Hydroformylation of 3-methyl-3-buten-1-ol (516 g, 6.00 moles) wascarried out in the same manner as Example 2 except that 15 mg (0.077milligrams atom on the rhodium atom basis) of [Rh(CO)₂ Cl]₂ was used asthe rhodium compound. The metallic rhodium precipitate was filtered offfrom the contents obtained, whereby 91% of the rhodium used wasrecovered. The reaction mixture (667 g) after filtration was analyzed bygas chromatography. Unreacted 3-methyl-3-buten-1-ol amounted to 0.01mole (conversion 99.8%) and the yield of2-hydroxy-4-methyltetrahydropyran was 1.7 moles (selectivity 28%). Theformation of 1.38 moles (selectivity 46%) ofbis(tetrahydro-4-methyl-2H-2-pyranyl) ether, 0.11 mole (selectivity3.7%) of tetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran, 0.07 mole(selectivity 2.3%) of5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal, 0.20 mole(selectivity 6.7%) oftetrahydro-2-(3-methyl-2-butenoxy)-4-methyl-2H-pyran, 0.40 mole(selectivity 6.7%) of isovaleraldehyde and 0.03 mole (selectivity 0.5%)of 3-methyl-2-buten-1-ol, among others, was also detected.

EXAMPLE 5

Hydroformylation of 3-methyl-3-buten-1-ol (516 g, 6.00 moles) wascarried out in the same manner as Example 2 except that 129 mg (0.063milligram atom on the rhodium atom basis) of active carbon supporting 5weight percent of metallic rhodium was used in lieu of Rh₄ (CO)₁₂. Therhodium-on-active carbon was separated by filtration from the contentsobtained and the reaction mixture was analyzed by gas chromatography.Unreacted 3-methyl-3-buten-1-ol amounted to 0.12 mole (conversion of3-methyl-3-buten-1-ol, 98%) and the yield of2-hydroxy-4-methyltetrahydropyran was 1.8 mole (selectivity 31%). Therewas also detected the formation of 1.38 moles (selectivity 46.0%) ofbis(tetrahydro-4-methyl-2H-2-pyranyl) ether, 0.11 mole (selectivity3.7%) of tetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran, 0.07 mole(selectivity 2.3%) of5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal, 0.19 mole(selectivity 6.3%) oftetrahydro-2-(3-methyl-2-butenoxy)-4-methyl-2H-pyran, 0.41 mole(selectivity 6.8%) of isovaleraldehyde and 0.05 mole (selectivity 0.8%)of 3-methyl-2-buten-1-ol.

COMPARATIVE EXAMPLE 2

Hydroformylation of 3-methyl-3-buten-1-ol was carried out in the samemanner except that 0.47 g (1.8 millimoles) of triphenylphosphine wasadded to the reaction system. After completion of the reaction, thesystem was returned to ordinary pressure, whereupon the rhodium compoundin the reaction mixture did not precipitate out, hence rhodiumseparation by filtration was impossible. Analysis of this reactionmixture by gas chromatography indicated that the conversion of3-methyl-3-buten-1-ol was as low as 21% and the selectivity toward2-hydroxy-4-methyltetrahydropyran was 85%.

EXAMPLE 6

A 1-liter stainless steel autoclave equipped with a magnetic stirrer wascharged with 430 g of 3-methyl-3-buten-1-ol, 125 g of hexane and, as therhodium compound, 3.4 mg (0.0182 milligram atom on the rhodium atombasis) of Rh₄ (CO)₁₂ in an atmosphere of a carbon monoxide-hydrogenmixed gas (mole ratio=1:1), and the reaction mixture was heated to 110°C. over 40 minutes under stirring while maintaining the pressure withinthe autoclave at 200 atmospheres (absolute) with a carbonmonoxide-hydrogen mixed gas (mole ratio=1:1). During the reactionperiod, the carbon monoxide-hydrogen mixed gas (mole ratio=1:1) wascontinuously fed into the autoclave through a pressure controller tomaintain the pressure within the autoclave at 200 atmospheres (absolute)while the effluent gas flow rate from the autoclave was adjusted atabout 5 liters/hr. After 5 hours of hydroformylation at 100° C.(autoclave inside temperature), the reaction mixture in the autoclavewas transferred with the aid of pressure to a 2-liter autoclave whichhad previously been purged with nitrogen gas, and the mixture wasstirred at 100° C. under nitrogen gas at 20 atmospheres (absolute) for30 minutes. Thereafter, the inside temperature was lowered to roomtemperature and the autoclave inside was depressurized. The reactionmixture (680 g) was taken out and the rhodium precipitate was separatedby filtration using a glass filter. Analysis by gas chromatography afterfiltration indicated that 17 g of unreacted 3-methyl-3-buten-1-olremained in the reaction mixture (conversion of 3-methyl-3-buten-1-ol,96%) and the yield of 2-hydroxy-4-methyltetrahydropyran was 456 g(selectivity based on 3-methyl-3-buten-1-ol converted, 82%).

COMPARATIVE EXAMPLE 3

The reaction procedure of Example 6 was followed except that 0.144 g(0.55 millimole) of triphenylphosphine was further added to the reactionsystem. Analysis of the reaction mixture by gas chromatography indicatedthat the conversion of 3-methyl-3-buten-1-ol was as low as 11%. Theselectivity toward 2-hydroxy-4-methylhydropyran based on3-methyl-3-buten-1-ol converted was 86%. In this example, the rhodiumcompound did not precipitate out upon depressurization after completionof the reaction.

EXAMPLES 7-16

An autoclave was charged with 3-methyl-3-buten-1-ol (430 g), one of therhodium compounds listed in Table 1 in an amount equivalent to 0.0182milligram atom on the rhodium atom basis and one of the organic solventsgiven in Table 1, and the hydroformylation was conducted in the samemanner as Example 6. The results obtained are shown in Table 1.

                                      TABLE 1                                     __________________________________________________________________________                    Organic solvent                                                                           Concen-                                                                            Conversion                                                                          Selectivity                                                        tration.sup.(1)                                                                    of IPEA.sup.(2)                                                                     toward HMP.sup.(3)                     Example                                                                             Rhodium compound                                                                        Name        (wt. %)                                                                            (%)   (%)                                    __________________________________________________________________________    Example 7                                                                           Rh.sub.4 (CO).sub.12                                                                    Decane      40   89    84                                     Example 8                                                                           Rh.sub.4 (CO).sub.12                                                                    Cyclohexane 30   95    83                                     Example 9                                                                           Rh.sub.4 (CO).sub.12                                                                    Methylcyclohexane                                                                         50   91    83                                     Example 10                                                                          (cyclo-C.sub.8 H.sub.12 RhCl).sub.2                                                     Benzene     15   89    81                                     Example 11                                                                          Rh.sub.4 (CO).sub.12                                                                    Toluene     20   90    81                                     Example 12                                                                          RhCl.sub.3.3H.sub.2 O                                                                   Methyl isobutyl ketone                                                                    40   87    84                                     Example 13                                                                          Rh.sub.4 (CO).sub.12                                                                    Diisopropyl ether                                                                         30   88    84                                     Example 14                                                                          Rh.sub.4 (CO).sub.12                                                                    Methyl acetate                                                                            30   78    84                                     Example 15                                                                          Rh.sub.4 (CO).sub.12                                                                    Hexane      3    92    62                                     Example 16                                                                          Rh.sub.4 (CO).sub.12                                                                    Ethanol     30   58    63                                     __________________________________________________________________________     Note                                                                          .sup.(1) The organic solvent concentration is the one in reaction mixture     at the time of charging (prior to pressurization with carbon                  monoxidehydrogen mixed gas).                                                  .sup.(2) IPEA: 3Methyl-3-buten-1-ol                                           .sup.(3) HMP: 2Hydroxy-4-methyltetrahydropyran                                .sup.(4) The selectivity toward HMP is based on 3methyl-3-buten-1-ol          converted.                                                               

EXAMPLE 17

The reaction procedure of Example 6 was followed except that the sameautoclave as used in Example 6 was charged with 344 g of3-methyl-3-buten-1-ol, 230 g of hexane and 3.6 mg (0.0192 milligram atomon the rhodium atom basis) of Rh₄ (CO)₁₂ and the reaction under carbonmonoxide-hydrogen mixed gas pressure was conducted for 4 hours, whereby665 g of a reaction mixture was obtained. The precipitate rhodium wasfiltered off from this mixture. Analysis of the reaction mixture by gaschromatography indicated that the conversion of 3-methyl-3-buten-1-olwas 94% and the selectivity toward 2-hydroxy-4-methyltetrahydropyranbased on 3-methyl-3-buten-1-ol converted was 86%. Distillation of thisreaction mixture gave 264 g of a low-boiling fraction mainly composed ofhexane. Gas chromatographic analysis of this distillate indicated thatit contained 29 g of isovaleraldehyde in addition to hexane. Thedistillation residue was fractionated under reduced pressure (25 mm Hg)to give 59 g of a distillate (column top temperature 50°-95° C.). Gaschromatographic analysis indicated that this distillate was composed of2 g of isovaleraldehyde, 21 g of unreacted 3-methyl-3-buten-1-ol, 12 gof 3-methyl-2-buten-1-ol and 23 g of 2-hydroxy-4-methyltetrahydropyran.At a column top temperature of 95° C., there was further obtained 332 gof a distillate, and this was 2-hydroxy-4-methyltetrahydropyran having apurity of not less than 99%. The yield of2-hydroxy-4-methyltetrahydropyran obtained as the distillate was 81.5%based on reacted 3-methyl-3-buten-1-ol.

EXAMPLE 18

Hydroformylation of 3-methyl-3-buten-1-ol was carried out in the samemanner as Example 6. Thereafter, the reaction mixture was transferredwith the aid of pressure to a 2-liter autoclave equipped with a magneticstirrer which had previously been charged with 25 g of activated carbon(GW; Kuraray Chemical Co., Ltd.), 500 g of water and 1 g oftriethanolamine, and the whole mixture was stirred for 20 minutes at 2atmospheres (absolute) under a carbon monoxide-hydrogen mixed gas (moleratio=1:1) at 110° C. After cooling to room temperature anddepressurization, the reaction mixture was then taken out from theautoclave through a filter to remove the activated carbon. The mixtureobtained was composed of two layers, namely organic layer and aqueouslayer, and each layer was analyzed by gas chromatography. It is foundthat the organic layer contained 14 g of unreacted 3-methyl-3-buten-1-olremained and 366 g of product 2-hydroxy-4-methyltetrahydropyran. On theother hand, in the aqueous layer, 1 g of 3-methyl-3-buten-1-ol remainedunreacted and there was also found 91 g of2-hydroxy-4-methyltetrahydropyran. Measurement of the rhodiumconcentration in the organic layer and aqueous layer revealed that 96%of the rhodium in the rhodium compound charged into the reaction systemhad been removed by adsorption on the activated carbon.

EXAMPLE 19

A 1-liter stainless steel autoclave equipped with thermometer, magneticstirrer, gas inlet, gas outlet and pressure controller and connected,via a pipe for liquid transfer with the aid of pressure, with a 2-literglass autoclave equipped with a magnetic stirrer was charged with 500 mlof hexane, and 0.0125 millimole/liter [0.050 milligram atom (as rhodiumatom)/liter] of Rh₄ (CO)₁₂ and the system atmosphere was thoroughlysubstituted with a carbon monoxide-hydrogen mixed gas (mole ratio=1:1).Thereafter, while maintaining the pressure within the stainlessautoclave at 150 atmospheres (absolute) with the above mixed gas, themixture was heated with stirring until the inside temperature reached toa constant temperature of 100° C. and, then, 75 g of3-methyl-3-buten-1-ol was continuously fed into the stainless autoclavethrough a constant-rate feed pump over 30 minutes. Throughout thereaction period, the same carbon monoxide-hydrogen mixed gas was fedinto the autoclave so that the pressure in the autoclave was maintainedat 150 atmospheres (absolute) while the rate of the effluent gas flowfrom the autoclave was adjusted to about 5 liters/hr. After completionof the feeding of 3-methyl-3-buten-1-ol, the reaction was still allowedto proceed with stirring under the same conditions for 2 additionalhours. After 2.5 hours of reaction in total, stirring was stopped andthe autoclave inside temperature was lowered quickly to around roomtemperature. Thereafter, the autoclave inside was depressurized to 20atmospheres (absolute) and a trace amount of the reaction mixture wastaken out from the autoclave and analyzed by gas chromatography. It wasfound that unreacted 3-methyl-3-buten-1-ol amounted to 1.5 g (conversionof 3-methyl-3-buten-1-ol, 98%) and the yield of2-hydroxy-4-methyl-hydropyran was 84 g (selectivity 85%).

The 2-liter glass autoclave equipped with a magnetic stirrer andconnected with the stainless steel autoclave was purged with a carbonmonoxide-hydrogen mixed gas (mole ratio=1:1) and charged with 500 ml ofwater and, then, the above reaction mixture was transferred with the aidof pressure from the stainless steel autoclave to the glass autoclave.When the transfer was complete, the system was maintained at a pressureof 5 atmospheres (absolute) in the mixed gas atmosphere and stirred inthis condition for 20 minutes for effect extraction. The extractiontemperature was 30° C. Upon termination of the stirring, the liquidmixture was separated into two layers. After standing for 10 minutes,the lower aqueous layer alone was taken out of the system takingadvantage of the system inside pressure. Such aqueous extract layer wasanalyzed by gas chromatography. It was found that 70% of the2-hydroxy-4-methyltetrahydropyran produced had been extracted into theaqueous layer.

The extraction residue layer in the glass autoclave was transferred withthe aid of pressure back to the stainless steel autoclave, and thehydroformylation of 3-methyl-3-buten-1-ol followed by extraction wasrepeated under the same conditions. In this manner, saidhydroformylation and extraction procedure was repeated five times in allwithout further addition of the rhodium compound or hexane. In the 2nd,3rd, 4th and 5th runs of the hydroformylation of 3-methyl-3-buten-1-ol,the conversion rates were 98%, 97%, 97% and 98%, respectively, and theselectivity toward 2-hydroxy-4-methyltetrahydropyran was constantly 85%.In each extraction, the 2-hydroxy-4-methyltetrahydropyran concentrationin the aqueous extract layer was in the range of 1.0-1.3 moles perliter. The dissolution of the rhodium compound into the aqueousextraction layer in the second and the subsequent extractions wasslight, namely within the range of 0.03-0.05 ppm in terms of rhodiumatom concentration.

EXAMPLE 20

The hydroformylation and extraction procedure of Example 19 was repeatedfive times except that the autoclave was charged with 500 ml ofcyclohexane and 0.025 millimole/liter of (cyclo-C₈ H₁₂ RhCl)₂ and thatthe reaction conditions were as follows: pressure, 200 atmospheres(absolute); temperature, 120° C.; reaction time after feeding of3-methyl-3-buten-1-ol, 1 hour (1.5 hours in total). Gas chromatographicanalysis of the liquid reaction mixture after completion of the reactionindicated that the conversion of 3-methyl-3-buten-1-ol was within therange of 98-99% and the selectivity toward2-hydroxy-4-methyltetrahydropyran was always 84%. In the second andsubsequent extractions, the 2-hydroxy-4-methyltetrahydropyranconcentration in the aqueous extract layer was within the range of1.0-1.3 moles/liter and the percentage extraction of2-hydroxy-4-methyltetrahydropyran into the aqueous layer was on theaverage 70%. The dissolution of the rhodium compound into the aqueousextract layer was as small as 0.05-0.08 ppm in terms of rhodium atomconcentration.

EXAMPLE 21

The hydroformylation and extraction procedure of Example 19 was repeatedfive times except that the autoclave was charged with 100 ml of tolueneand 0.025 millimole/liter of Rh₄ (CO)₁₂, that the reaction temperaturewas 90° C. and that 300 ml of water was used for extraction. Aftercompletion of the reaction, the reaction mixture was analyzed by gaschromatography and it was found that the conversion of3-methyl-3-buten-1-ol was 94-95% and the selectivity toward2-hydroxy-4-methyltetrahydropyran was always 85%. In the second andsubsequent extractions, the 2-hydroxy-4-methyltetrahydropyranconcentration in the aqueous extract layer was within the range of1.3-1.9 moles/liter and percentage extraction of2-hydroxy-4-methyltetrahydropyran into the aqueous layer was on theaverage 42%. The dissolution of the rhodium compound into the aqueousextract layer was slight, namely within the range of 0.07-0.15 ppm interms of rhodium atom concentration.

EXAMPLE 22

The hydroformylation and water extraction procedure of Example 19 wascarried out (once). The conversion of 3-methyl-3-buten-1-ol in thehydroformylation was 98%, the selectivity toward2-hydroxy-4-methyltetrahydropyran was 85%, the2-hydroxy-4-methyltetrahydropyran concentration in the aqueous extractlayer in the water extraction was 0.91 mole/liter, and the dissolutionof the rhodium compound into the aqueous layer was as small as 0.05 ppmin terms of rhodium atom concentration. This aqueous solution wastransferred to a 2-liter flask equipped with a stirrer and mixed with500 ml of isopropyl acetate under stirring. The resultant mixture wasallowed to stand and the upper isopropyl acetate layer was analyzed bygas chromatography. The 2-hydroxy-4-methyltetrahydropyran concentrationin said isopropyl acetate solution was found to be 0.71 mole/liter.

EXAMPLES 23 TO 25

The hydroformylation, water extraction and reextraction procedure ofExample 22 was repeated in the same manner except that each extractantgiven in Table 2 was used in lieu of the organic extractant isopropylacetate in the reextraction step. The 2-hydroxy-4-methyltetrahydropyranconcentration in the organic extractant layer after reextraction asattained is shown in Table 2.

                  TABLE 2                                                         ______________________________________                                                             HMP.sup.(1) concentration                                Organic extractant   (mole/liter)                                             ______________________________________                                        Example 23                                                                            Methyl isobutyl ketone                                                                         0.70                                                 Example 24                                                                            Benzene          0.61                                                 Example 25                                                                            3-Methyl-3-buten-1-ol                                                                          0.66                                                 ______________________________________                                         Note:                                                                         .sup.(1) HMP: 2Hydroxy-4-methyltetrahydropyan.                           

EXAMPLE 26

The first hydroformylation and water extraction was carried out in thesame manner as Example 19. After completion of the reaction, thereaction mixture was analyzed by gas chromatography and it was foundthat the conversion of 3-methyl-3-buten-1-ol was 98% and the selectivitytoward 2-hydroxy-4-methyltetrahydropyran was 85%.

A 2-liter three-necked flask was connected with the above-mentioned2-liter glass autoclave for water extraction, purged with nitrogen, andcharged with 500 ml of isobutyl acetate. Thereafter, the aqueous extractobtained by water extraction was transferred from the glass autoclave tosaid flask with the aid of pressure. The extraction residue layer in theglass autoclave was transferred with the aid of pressure to thestainless steel autoclave and the hydroformylation of3-methyl-3-buten-1-ol was again performed under the same conditions andby the same procedure, during which the isobutyl acetate and the aboveaqueous extract in the flask were mixed with stirring at 30° C. for 10minutes and then allowed to stand for 10 minutes, followed by transfer,with the aid of pressure, of the lower aqueous layer to the glassautoclave and drawing out the upper isobutyl acetate layer from thesystem within the flask. Analysis of such isobutyl acetate solution bygas chromatography indicated that 53% of the2-hydroxy-4-methyltetrahydropyran formed in the first hydroformylationrun had been taken out of the system in the form of isobutyl acetatesolution.

In this manner, the serial procedure comprising hydroformylation, waterextraction and isobutyl acetate extraction was repeated to five times inall. In the hydroformylation step, the conversion of3-methyl-3-buten-1-ol was 97-88% and the selectivity toward2-hydroxy-4-methyl-tetrahydropyran was constantly 85%. The amounts of2-hydroxy-4-methyltetrahydropyran taken out in the form of isobutylacetate solution in the 2nd, 3rd, 4th and 5th extraction with isobutylacetate were 0.58 mole, 0.66 mole, 0.71 mole and 0.74 mole,respectively.

EXAMPLE 27

A 1-liter autoclave equipped with a magnetic stirrer was charged with500 g (3.85 moles) of 3-methyl-3-butenyl acetate and, as the rhodiumcompound, 10 mg (0.0534 milligram atom on the rhodium atom basis) of Rh₄(CO)₁₂ under the atmosphere of carbon monoxide-hydrogen mixed gas (moleratio 1:1). The system atmosphere was thoroughly substituted with thecarbon monoxide-hydrogen mixed gas (mole ratio 1:1). Thehydroformylation reaction was carried out by heating the autoclavecontents at 100° C. with stirring for 5 hours while maintaining thepressure within the autoclave at 180 atmospheres (absolute) with saidmixed gas. During the reaction, the carbon monoxide-hydrogen mixed gas(mole ratio 1:1) was continuously fed through a pressure controller tothereby maintain the system pressure at 180 atmospheres (abolute), whilethe effluent gas from the autoclave was adjusted to about 5 liters/hour.Then, the reaction mixture in the autoclave was transferred with the aidof pressure to a 2-liter autoclave previously charged with 700 mg ofwater and 5 g of activated carbon (GA; Kuraray Chemical Co., Ltd.) andthe resultant mixture was stirred at 100° C. under a carbonmonoxide-hydrogen mixed gas (mole ratio 1:1) at a pressure of 5atmospheres (absolute) for 30 minutes. After cooling and depressuring,the activated carbon was filtered off from the contents, whereby 98% ofthe rhodium used was adsorbed on the activated carbon and separated fromthe reaction mixture. Water was removed by phase separation and theorganic layer obtained was distilled under reduced pressure to give 530g of 5-acetoxy-3-methylpentanal as a fraction boiling at 71°-72° C.under 10 mm Hg (yield based on 3-methyl-3-butenyl acetate charged, 86%).

EXAMPLE 28

A 2-liter autoclave equipped with a magnetic stirrer was charged with 40g of Raney nickel pretreated with dilute aqueous acetic acid having a pHof 4, together with 600 ml of ethanol and 500 ml of water. The solutionshowed a pH of 5.0. The system atmosphere was thoroughly substitutedwith hydrogen gas and then the autoclave contents were maintained at aconstant temperature of 100° C. under stirring while maintaining theautoclave inside pressure at 50 atmospheres (absolute) with hydrogengas. To this system, there was fed 670 g of the hydroformylationreaction mixture obtained in Example 2 continuously over 6 hors througha constant flow rate pump. Throughout the reaction period, hydrogen gaswas continuously fed through a pressure controller to thereby maintainthe system pressure at 50 atmospheres (absolute), while the flow rate ofthe effluent gas from the autoclave was adjusted at 20 liters/hour.After completion of the continuous feeding of the reaction mixture,stirring was continued for an additional hour. After cooling anddepressurizing, the contents were taken out from the autoclave, and thecatalyst was filtered off. The reaction mixture thus obtained had a pHof 5.2 and was analyzed by gas chromatography, which showed that 62 g ofisoamyl alcohol and 622 g of 3-methylpentane-1,5-diol had been formed.The yield of 3-methylpentane-1,5-diol was 88% based on the3-methyl-3-buten-1-ol charged into the hydroformylation reaction systemin Example 2.

EXAMPLE 29

The hydrogenation reaction was carried out in the same manner as Example28 except that the autoclave was charged with 40 g of Raney nickeltogether with 600 ml of ethanol and 500 ml of water, followed byadjustment of the pH of the solution to 5.0 by adding 1.5 g of aceticacid and that 670 g of hydroformylation reaction mixture obtained inExample 3 was used. After completion of the reaction, the reactionmixture had a pH of 5.1. Analysis of this reaction mixture by gaschromatography indicated the formation of 3-methylpentane-1,5-diol in ayield of 87% based on the 3-methyl-3-buten-1-ol charged into thehydroformylation reaction system in Example 3. Isoamyl alcohol was theonly byproduct.

EXAMPLE 30

Hydrogenation of the reaction mixture (667 g) obtained after filtrationin Example 4 was carried out in the same manner as Example 28 exceptthat a Raney nickel catalyst pretreated with a diluted hydrochloric acidhaving a pH of 4 was used (pH of the solution at the time of catalystcharge, 5.0). There was obtained 613 g of 3-methyl-pentane-1,5-diol. Thereaction mixture at the time of completion of the reaction had a pH of5.1. The yield of 3-methylpentane-1,5-diol was 86% based on the3-methyl-3-buten-1-ol charged into the hydroformylation reaction systemin Example 4.

EXAMPLE 31

Hydrogenation of the hydroformyltion reaction mixture (665 g) obtainedin Example 5 was carried out in the same manner as Example 28 exceptthat the autoclave was charged with 40 g of Raney nickel, 600 ml ofethanol and 500 ml of water, followed by adjustment of the pH of thesolution to 3 by adding 2.5 g of acetic acid. After completion of thereaction, the reaction mixture obtained had a pH of 3. Analysis of saidmixture by gas chromatography showed the formation of3-methylpentate-1,5-diol in a yield of 86% (based on the3-methyl-3-buten-1-ol charged into the hydroformylation reaction systemin Example 5).

EXAMPLE 32

Hydroformylation of 3-methyl-3-buten-1-ol (516 g) was carried out in thesame manner as Example 3. The precipitate metallic rhodium was filteredoff from the reactor contents to give 670 g of a hydroformylationproduct. This product was hydrogenated in the same manner as Example 28except that the autoclave was charged with 40 g of Raney nickel and1,100 ml of water, followed by adjustment to the pH of the solution to 4by adding 1.8 g of acetic acid. After completion of the reaction, thereaction mixture had a pH of 4. Gas chromatographic analysis of suchreaction mixture showed the formation of 3-methylpentane-1,5-diol in ayield of 84% based on the 3-methyl-3-buten-1-ol charged into thehydroformylation reaction system.

EXAMPLE 33

Hydroformylation of 3-methyl-3-buten-1-ol (516 g) was carried out in thesame manner as Example 3. The precipitate metallic rhodium was filteredoff from the reactor contents obtained to give 670 g of ahydroformylation product. Said hydroformylation product was hydrogenatedin the same manner as Example 28 except that the autoclave was chargedwith 50 g of a powdery nickel-on-diatomaceous earth catalyst (nickelcontent 50% by weight) together with 600 ml of ethanol and 500 ml ofwater and that the autoclave inside temperature was raised to andmaintained at 140° C. with stirring while maintaining the autoclaveinside pressure at 100 atmospheres (absolute) with hydrogen gas.Analysis, after completion of the reaction, of the reaction mixtureindicated the formation of 3-methylpentane-1,5-diol in a yield of 84%based on the 3-methyl-3-buten-1-ol charged into the hydroformylationreaction system.

COMPARATIVE EXAMPLE 4

Hydroformylation of 3-methyl-3-buten-1-ol (516 g) was carried out in thesame manner as Example 2. The precipitate metallic rhodium was filteredoff from the reactor contents obtained to give 670 g of ahydroformylation reaction mixtue. Gas chromatographic analysis showedthat said reaction mixture contained 0.01 mole of unreacted3-methyl-3-buten-1-ol (conversion of 3-methyl-3-buten-ol, 99.8%) and 2.0moles of 2-hydroxy-4-methyltetrahydropyran (selectivity 33%).

An autoclve was charged with 40 g of Raney nickel together with 1 literof ethanol. Thereto was fed continuously the hydroformylation reactionmixture (670 g) over 6 hours while maintaining the autoclave insidetemperature at 100° C. with stirring under a hydrogen pressure of 50atmospheres (absolute). Thereafter, the reaction was continued forfurther 1 hour with stirring, the contents were then taken out and thecatalyst was separated by filtration. Gas chromatographic analysis ofthe reaction mixture obtained showed that the yield of3-methylpnetane-1,5-diol was only 260 g (yield based on the3-methyl-3-buten-1-ol charged into the hydroformylation reaction system,37%).

COMPARATIVE EXAMPLE 5

Hydroformylation of 3-methyl-3-buten-1-ol (516 g) was carried out in thesame manner as Example 2. The precipitate metallic rhodium was filteredoff from the contents obtained. Gas chromatographic analysis showed thatthe thus-obtained reaction mixture (670 g) contained 0.01 mole ofunreacted 3-methyl-3-buten-1-ol (conversion of 3-methyl-3-buten-1-ol,99.8%) and 2.0 moles of 2-hydroxy-4-methyltetrahydropyran (selectivity33%).

An autoclave was charged with 40 g of Raney nickel together with 1 literof water. This solution has a pH of 8. Thereto was fed continuously theabove hydroformylation reaction mixture (670 g) over 6 hours whilemaintaining the autoclave inside at a hydrogen pressure of 50atmospheres (absolute) and a temperature of 100° C. with stirring.Thereafter, the reaction was continued for 1 hour with stirring. Aftercooling and depressurizing, the contents were taken out and the catalystwas separated by filtration. The reaction mixture obtained had a pH of8. Analysis of this reaction mixture by gas chromatography showed thatthe yield of 3-methyl-pentane-1,5-diol was only 275 g (yield based onthe 3-methyl-3-buten-1-ol charged into the hydroformylation reactionsystem, 39%).

EXAMPLE 34 (a) Hydroformylation oftetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran

A 100-ml stainless steel autoclave equipped with a magnetic stirrer wascharged with 30 g (0.163 mole) oftetrahydro-2-(3-methyl-3-butenoxy)-4-methyl--2H-pyran, 20 ml of hexaneand 0.14 mg of Rh₄ (CO)₁₂. The system atmosphere was thoroughlysubstituted with a mixed gas composed of hydrogen and carbon monoxide(hydrogen/carbon monoxide mole ratio 1/1), followed by pressurization to250 atmospheres (absolute) with the same mixed gas. With stirring, themixture was heated to 100° C. over 30 minutes and maintained at the sametemperature for 5 hours to thereby effect the hydroformylation.Throughout the reaction period, the reactor inside pressurre was alwaysmaintained at 250 atmospheres (absolute) taking advantage of a pressurecontroller while the off-gas was continuously drawn out of the reactionsystem at a flow rate of about 5 liters/hour. After completion of thereaction, the reactor contents were cooled and depressurized to ordinarypressure, and the reaction mixture was taken out. The reaction mixturewas heated to 100° C. in a nitrogen atmosphere and then cooled, and theresulting precipitate (rhodium compound) was filtered off. Removal ofthe hexane from the filtrate by distillation gave 34.8 g of ahydroformylation product as a distillation residue. A main component ofthis residue was 5-(tetrahydro-4-methyl-2H-2-pyranoxy)-3-methylpentanal.

(b) Hydrogenation of the hydroformylation product

A 300ml stainless steel autoclave equipped with a magnetic stirrer wascharged with 100 ml of methanol, 50 ml of water, 10 g of the abovehydroformylation product and 2 g of a powdery nickel-on-diatomaceousearth catalyst (nickel content 50% by weight). The hydroformylationproduct was hydrogenated at 140° C. with stirring for 2 hours whilemaintaining the hydrogen pressure at 50 atmospheres (absolute). Aftercompletion of the hydrogenation reaction, the reaction mixture wasanalyzed by gas chromatography. It was found that the conversion of thehydroformylation product was 100% and the hydrogenation product wascomposed of 97.0 mole percent of 3-methylpentane-1,5-diol, 2.5 molepercent of 2-isopropylpropane-1,3-diol and 0.5 mole percent of isoamylalcohol. The catalyst was filtered off from the reaction mixture, themethanol and water were distilled off and the residue was distilledunder reduced pressure to give 10.5 g of pure 3-methylpentane-1,5-diolas a fraction boiling at114° C./4 mm Hg.

(c) Production of tetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyranfrom the Hydroformulation Product

A 100-ml three-necked flask equipped with condenser, stirrer andthermometer was charged with 10 g of the above hydroformylation product,8.6 g (0.1 mole) of 3-methyl-3-buten-1-ol, 20 ml of hexane and 1 g ofactive clay, and the mixture was stirred at 65° C. for 1 hour. Thereaction mixture thus obtained was analyzed by gas chromatography and itwas found that the conversion of the hydroformylaton product was 100%and the yield of tetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyranwas 96% based on the 3-methyl-3-buten-1-ol converted.

EXAMPLE 35 (a) Production of 2-hydroxy-4-methyltetrahydropyran

The procedure of Example 17 was repeated to give2-hydroxy-4-methyltetrahydropyran.

(b) Simultaneous production of β-methyl-δ-valerolactone and3-methylpentane-1,5-diol

A 100-ml three-necked flask equipped with dropping funnel, condenser,stirrer and thermometer was charged with 0.5 g of a powdery (passingthrough a 200-mesh sieve) copper chromite catalyst (N 203; CuO-Cr₂ O₃,0.5% MnO₂ ; Nikki Chemical Co., Ltd.) and 25 ml of dioctyl phthalate.The flask inside was purged with a nitrogen gas atmosphere at 1atmosphere (absolute) and then the solution was heated to 160° C. withstirring, followed by dropwise addition, at 160° C., of 25 g of the2-hydroxy-4-methyltetrahydropyran obtained above from the droppingfunnel over 10 minutes. Thereafter, the resulting mixture was stirred at160° C. for further 50 minutes and, then, the reaction mixture wascooled. Gas chromatographic analysis of the reaction mixture obtainedindicated that the conversion of 2-hydroxy-4-methyltetrahydropyran was99%, with the formation of β-methyl-δ-valerolactone and3-methylpentane-1,5-diol in selectivities of 57% and 43%, respectively.

EXAMPLES 36-39 AND COMPARATIVE EXAMPLES 6-7

The procedure of Example 35 (b) was repeated at a reaction temperaturespecified in Table 3 using a catalyst given in Table 3. The resultsobtained in this manner are shown in Table 3.

                                      TABLE 3                                     __________________________________________________________________________    Example or       Reaction                                                                             Conversion                                            Comparative      temperature                                                                          of HMP.sup.(1)                                                                      Selectivity (%).sup.(2)                         Example                                                                              Catalyst  (°C.)                                                                         (%)   MVL.sup.(3)                                                                        MPD.sup.(4)                                __________________________________________________________________________    Example 36                                                                           Copper-zinc                                                                             160    99    57   43                                                oxide.sup.(5)                                                          Example 37                                                                           Copper-chromium-                                                                        140    91    58   42                                                zinc oxide.sup.(6)                                                     Example 38                                                                           Copper chromite.sup.(7)                                                                 180    100   59   41                                         Example 39                                                                           Copper chromite.sup.(7)                                                                 120    82    56   44                                         Comparative                                                                          Copper chromite.sup.(7)                                                                 210    100   94   6                                          Example 6                                                                     Comparative                                                                          Copper chromite.sup.(7)                                                                 100    19    57   43                                         Example 7                                                                     __________________________________________________________________________     Notes:                                                                        .sup.(1) HMP: 2hydroxy-4-methyltetrahydropyran                                .sup.(2) Selectivity toward methyl-valerolactone or                           3methylpentane-1,5-diol based on 2hydroxy-4-methyltetrahydropyran             converted.                                                                    .sup.(3) MVL: methyl-valerolactone                                            .sup.(4) MPD: 3methylpentane-1,5-diol                                         .sup.(5) CuO--ZnO; Catalyst N 211 (Nikki Chemical Co., Ltd.) pulverized t     enable passage through a 200mesh sieve.                                       .sup.(6) CuO--Cr.sub.2 O.sub.3 --ZnO; Catalyst C44 (Catalysts & Chemicals     Inc., Far East) pulverized to enable passage through a 200mesh sieve.         .sup.(7) CuO--Cr.sub.2 O.sub.3, 0.5% MnO.sub.2 ; Catalyst N 203 (Nikki        Chemical Co., Ltd.)                                                      

EXAMPLE 40 (a) Production of 2-hydroxy-4-methyltetrahydropyran

The procedure of Example 17 was repeated to give2-hydroxy-4-methyltetrahydropyran.

(b) Simultaneous production of β-methyl-δ-valerolactone and3-methylpentane-1,5-diol

A 100-ml stainless steel autoclave equipped with raw material inlet, gasinlet and magnetic stirrer was charged with 0.5 g of a powdery (passingthrough a 200-mesh sieve) copper chromiate catalyst (N 203; CuO-Cr₂ O₃,0.5% MnO₂ ; Nikki Chemical Co., Ltd.) 50 g of triethylene glycoldimethyl ether and 10 g of the 2-hydroxy-4-methyltetrahydropyranobtained above. The autoclave inside was pressurized to 10 atmospheres(absolute) with hydrogen gas. The mixture was heated to 140° C. over 15minutes with vigorous stirring and then stirring was continued at thattemperature for further 60 minutes. Throughout the reaction period, thepressure always maintained at 10 atmospheres (absolute) while adjustingsuch that the hydrogen gas flowed out as the off-gas at a rate of 10liters/hour. After completion of the reaction, the autoclave inside wasreturned to ordinary temperature and pressure, and the reaction mixturewas taken out. Analysis of this mixture by gas chromatography showedthat the conversion of 2-hydroxy-4-methyltetrahydropyran was 98.5%, withthe formation of β-methyl-δ-valerolactone and 3-methypentane-1,5-diol inselectivities of 46% and 54%, respectively.

EXAMPLE 41-44

The procedure of Example 40 (b) was repeated at a reaction pressure andreaction temperature each given in Table 4. The results obtained areshown in Table 4.

                  TABLE 4                                                         ______________________________________                                        Reaction       Reaction Conver-                                               pressure       temper-  sion of  Selectivity                                  [atmospheres   ature    HMP.sup.(1)                                                                            (%).sup.(2)                                  Example (absolute)]                                                                              (°C.)                                                                           (%)    MVL.sup.(3)                                                                         MPD.sup.(4)                          ______________________________________                                        Example 41                                                                            17         140      96     40    60                                   Example 42                                                                            6          180      99     49    51                                   Example 43                                                                            11         130      88     44    56                                   Example 44                                                                            31         180      99     17    83                                   ______________________________________                                         Notes:                                                                        .sup.(1) HMP: 2hydroxy-4-methyltetrahydropyran                                .sup.(2) Selectivity toward methyl-valerolactone or                           3methylpentane-1,5-diol based on 2hydroxy-4-methyltetrahydropyran             converted.                                                                    .sup.(3) MVL: methyl-valerolactone                                            .sup.(4) MPD: 3methylpentane-1,5-diol                                    

What is claimed is:
 1. A method of producing 3-methylpentane-1,5-diolwhich comprises reacting a compound of the general formula ##STR18##wherein R⁶ is a hydrogen atom or a tetrahydro-4-methyl-2H-2-pyranylgroup, with carbon monoxide and hydrogen in the presence of a rhodiumcompound free from modification by a ligand containing an elementbelonging to the group V of the periodic table and hydrogenating thehydroformylation product obtained in the presence of water, ahydrogenation catalyst and an acidic substance.
 2. The method of claim1, wherein the compound of general formula (I') istetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyran and wherein part ofthe hydroformylation product obtained is reacted with3-methyl-3-buten-1-ol in the presence of an acid catalyst to therebyconvert the same to tetrahydro-2-(3-methyl-3-butenoxy)-4-methyl-2H-pyranand the latter is used as the raw material in the hydroformylationreaction.
 3. The method of claim 1, wherein the amount of water is notless than about 0.05 parts by weight per part by weight of thehydroformylation product.
 4. The method of claim 1, wherein said acidicsubstance is an organic acid.